This is our 4th renewal application to be a part of the NICHD Maternal-Fetal Medicine Units (MFMU) Network. In this application we describe the qualifications and experience of the maternal-fetal medicine faculty and research team at UT Southwestern and Parkland Hospital and the facilities and patient population available to carry out research protocols sponsored by the MFMU Network. In 2014, there were 10,036 obstetrical patients delivered at Parkland Hospital and approximately 56% were high-risk. Pregnancy complications of particular interest to the MFMU Network, for example, preterm birth, preeclampsia, and diabetes are well represented in the obstetrics population at Parkland Hospital. We emphasize that our now 20-year participation as a MFMU Network site has been greatly enhanced by the fact that our center is built around a single large perinatal hospital which is consistent with the attributes specified in RFA-HD-16-019. A computerized perinatal database for all births at Parkland Hospital, operational since 1982, continues to be a centerpiece in our center's academic productivity as well as an important component of our center's successful participation in the MFMU Network. Indeed UT Southwestern's MFMU Network site has frequently been a leading recruiter for Network protocols. We emphasize that we also have been a leader in protocol adherence and completion. In this last 5-year cycle, our center continued to lead the successful annual follow-up of offspring and mothers enrolled in A Randomized Trial of Thyroxine Therapy for Subclinical Hypothyroidism or Hypothyroxinemia Diagnosed During Pregnancy (TSH) study. This included establishing a ground-breaking satellite site for TSH follow-up exams in Mexico City. Throughout our participation, we have been active in all aspects of the MFMU Network, including concept proposal, subcommittee participation, and manuscript preparation. In this application we not only look backward to review our past contributions to the Network but we also endeavor to look forward. Thus, for the next 5-year cycle at our center we propose three aims: In Aim #1 we emphasize the importance of continuing the Network tradition of disciplined evaluation of obstetrical interventions at our center. In Aim #2, we look to the future and suggest that the Network tradition of rigorous trials be broadened to include large and simple trials that could offer significant economic advantages. In Aim #3, we again look to the future and propose to intensify our center's recently renewed basic science research capability to include using biologic fluids routinely obtained in the course of Network studies. We are of the view that our large highly organized obstetrics public healthcare center is of value to the Network as the Network continues its legacy as the premier American platform for obstetric care outcomes research.